Characteristics of B, Zn and Se in stream sediments of Tanzania and their agricultural applications: Based on 1:1000000 geochemical survey

Tanzania is located in eastern Africa with a predominantly agricultural ecomomy, the potential for developing and utilizing cultivated land are promising, but scientific guidance is required. B, Zn and Se are essential micronutrients for plants and human body with crucial biological functions, in particular, Se is significant for human health and considered as “the king of anti-cancer”. As these elements required by human or plants are mainly absorbed from soil directly or indirectly, therefore, it is important to understand the contents and distributions of them in the soil of cultivated land for guiding agricultural production. In this work, low-density geochemical survey at the scale of 1:1000000 was carried out in Tanzania, and the results show that the concentrations of B, Zn and Se in stream sediments are low and their distributions are heterogeneous. According to the distributions of geological units, the existing cultivated land resources can be divided into five regions in Tanzania. Compared with the national background values, the concentrations of B, Zn and Se are insufficient overall but enriched locally in these regions. In general, element concentrations in stream sediments and soil have a positive correlation because of their similar sources, which is essential in agriculture application. Based on the information provided by low-density geochemical data and maps, the Se-sufficient and Se-rich regions were delineated in Tanzania, where can be used to develop Se-rich industries. Finally, this paper believes that geochemical survey is a powerful tool for cultivated land evaluation, agriculture management and land development.

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